Device and method for delivering a lubricating and/or cooling fluid in machining

ABSTRACT

The invention concerns a method and a device to deliver a cooling and/or lubricating fluid near the contact area between a tool and a workpiece being mechanical machined, wherein some “airless” type nozzles are provided to atomize the lubricating/cooling fluid.

FIELD OF THE INVENTION

The present invention concerns a device and a method for delivering alubricating and/or cooling fluid (also known as metalworking fluids) inthe field of machinings.

In particular, the present invention is applicable in all thosemachinings which provide contact between a tool and a workpiece in orderto remove material from the workpiece itself, both in case of machiningbeing operated with specific cutting tools (for example turning,milling, drilling, etc.) and in case of machining being operated with anundefined cutter tool (for example grinding, lapping, etc.).

BACKGROUND OF THE INVENTION

As a way of example, specific reference will be made below to machiningswith chip removal which are operated by specific cutting tools onmetallic materials, but it has to be understood that principles of thepresent invention are equally applicable to generally all machinings andto all types of materials (for example ceramic materials, minerals,etc.), machining of which may require lubrication and/or cooling.

In machinings with chip removal the tool is subject to wear, whichprincipally occurs on the cutting edge of the tool, due to the frictionat the contact areas workpiece-tool-chip, to high mechanical loads andto high thermal stresses. In particular conditions, contact pressure canachieve values up to 1500 N/mm² and temperature at the chip-toolinterface can also exceed 1100° C.

The source of all wear problems of a tool is however referable to theheat which substantially generates because of plastic deformation of thematerial and of friction which mostly occurs in the point where chipcontacts the surface of the tool.

In the related art lubricating and/or cooling fluids (metalworkingfluids) are then utilized which are generally constituted by oileventually mixed or emulsified in water. In particular, as it frequentlyhappens, the lubricating and cooling fluid is constituted by a mix or anemulsion of oil in water in order to exploit lubricating characteristicsof the oil together with the high heat exchange efficacy of the water.In fact lubricating and cooling fluids have the dual task both ofreducing friction between mutually contacting parts and of removing theheat thus generated.

Since a large amount of heat generated during the machining is absorbedby the chip, there is the problem of removing heat from the tool, andthis substantially means cooling the tool in order to limit, as much aspossible, wear of the tool itself.

As a matter of fact, it has been found from research in this field thatduration of a tool is directly related to the cutting temperature (seefor example see “TECNOLOGIA MECCANICA E STUDI DI FABBRICAZIONE”—F.Giusti e M. Santochi—Casa Editrice Ambrosiana).

As a confirmation of results of this research, it has actually foundthat also a low percentage reduction of the cutting temperature canhighly improve tool duration. As way of example, for a tool provided totolerate a maximum temperature of 600° C., it has been found that areduction in the cutting temperature of about 30° C. (from 510° C. to480° C.) can improve duration of the tool of about five times (fromabout 20 to about 100 minutes).

One of the most diffused lubricating and cooling systems involvespredisposition of spouts of lubricant and coolant fluid which aredirected toward the working area, or rather toward the contact areabetween the tool and the workpiece. However, only the fluid portionwhich flows contacting the workpiece during its machining is able toremove part of the heat in the area of interest.

Consequently, in order to be sufficiently effective, these known systemsrequire high fluid flow rates, at variable pressures, depending on powerof the working machine or depending on the volume of removed chip (forexample according to standard UNI ISO8688). However, heat removalachievable with such systems often appears insufficient in particularconditions depending on machining parameters, like for example cuttingspeed and/or depth.

Moreover it is opportune to point out that traditional lubricating andcooling systems require a collection tank having sufficient capacity toallow heat exchange between the recovered metalworking fluid and theenvironment before the fluid itself is again reintroduced in thecircuit. For this reason, collection tanks are generally designed tohave a capacity variable from 5 to 8 times the maximum flow rate of thecircuit and then are particularly cumbersome.

For these reasons, systems have been provided wherein the fluid,constituted exclusively by lubricant oil, is directed toward the workingarea in an atomized form, i.e. with the fluid being sprayed in extremelysmall droplets by way of a pressurized air flow according to well knownworking principles of airbrushes. The carrier of the so formed fluiddroplets is constituted by the same pressurized air flow.

If from one side, considering that a droplet of the lubricating fluidhas a substantially spherical shape (maximum surface for a givenvolume), it is possible to improve efficiency of heat exchange betweenthe lubricating fluid and the tool, as well as between the lubricatingfluid and the surrounding setting, from the other side adoption oflubricating oil alone, without any addition of water, principallyachieves a lubricating function but does not permit to achieve theeffective heat removal which is guaranteed by the high heat exchangecapacity of water. These known systems, also known in the art as“minimal”, permit to limit fluid flow rates compared to direct flowsystems, but have some drawbacks quite related to theformation-and-conveying technique of droplets toward the area ofinterest.

First of all, the atomization technique itself by way of an air jetinvolves formation of particles having not homogeneous dimensions and,in particular, formation of particles having dimensions much larger thanothers. Consequently, largest particles tend to agglomerate because ofmolecular cohesion forces, and the droplets formed in this way tend toslip away from the chip actually preventing formation of a stable filmof fluid between the tool and the chip. An indication of this drawbackis made evident from the formation of droplets of large dimensions nearthe area of interest.

Secondly, the same air flow which carries fluid droplets tends to“bounce” against surfaces where is directed. Bouncing air carries fluiddroplets which are then sent away from the interested area. Because ofthis phenomenon, the amount of droplets which reaches the interestedarea is reduced, further preventing formation of a stable film oflubricating fluid at contacting points between tool and chip.

Moreover, the same carrier air flow generates vortexes which keepdroplets of fluid in suspension. These droplets do not arrive at thearea of interest and, together with droplets carried by the bounced air,tend to promote formation of “fog”, which results particularlyundesirable mostly for safety reasons. Lubricating fluids, in fact, canbe toxic, and in these cases it is therefore indispensable to providesuction supplies suitably designed to contrast fog enhancement.

It is necessary to add that, in “minimal” systems, efficacy of apossible aqueous component, in case it was added to the lubricating oil,may anyway be impaired by partial evaporation caused by the air flow onthe smallest water droplets.

SUMMARY OF THE INVENTION

This being stated, the task of the present invention is to provide amethod and a lubricating-cooling device which allows overcoming of priorart drawbacks.

In the scope of this task, it is a general object of the presentinvention to provide a device and a method for delivering a coolingand/or lubricating fluid which allow to efficiently cool the tooladopted for machining, as well as to effectively lubricate the interfacebetween the tool and the machined workpiece.

It is a particular object of the present invention to provide a methodand a device for lubricating-cooling which permit generation of aneffective flow of lubricant and cooling fluid between the tool and themachined workpiece.

It is another object of the present invention to provide a method and adevice of the aforesaid type which allow to limit, as much as possible,the flow rate, and therefore the consumption of the cooling-lubricatingfluid.

It is a further object of the present invention to provide a method anda device of the aforesaid type which allow highly reduction of residualrisks related to the eventual toxicity of the cooling-lubricating fluid.

These objects are achieved by the present invention which concerns adevice for delivering a lubricating and/or cooling fluid near thecontact area between a tool and a workpiece being machined, comprisingat least a circuit for circulation of the fluid and delivering means todeliver the fluid near, or in correspondence of, the contact areabetween the tool and the workpiece, characterized in that deliveringmeans include one or more nozzles of the airless type to atomize thefluid.

The wording “airless” is intended to identify those nozzles wherein“pulverization” of the fluid is mechanically achieved, i.e. bysubmitting the fluid at a certain pressure and making it pass through aduct having a particular geometrical shape near the delivery opening ofthe nozzle. In this way a pulverization, which sometimes is defined“hydraulic” (or “atomization”), is obtained, which is in contrapositionto that defined “pneumatic” (or “nebulization”) typical of known minimalsystems.

The invention also concerns a method for delivering a lubricating and/orcooling fluid near the contact area between a tool and a workpiece beingmachined, wherein the fluid is supplied through a circuit and deliverednear, or in correspondence of, the contact area between the tool and theworkpiece, characterized in that delivering of the fluid is carried outby its atomization through one or more airless nozzles.

“Airless” nozzles adopted according the present invention are generallyfor operating at particularly high pressures, typically at maximumpressures up to 600 bar. Nevertheless, according to the presentinvention, the fluid is supplied to nozzles having pressures not higherthan 150 bar and, preferably, having pressures from about 5 bar to about70 bar.

Moreover, it is possible to have an effective lubricating and coolingoperation also with particularly low fluid flow rates, from 10 to 100times lower than flow rates of traditional systems. This means that thesystem supplying the lubricating and cooling fluid has reduced power anddimensions, in particular collection tanks are less cumbersome, sopermitting greater accuracy in the fluid treatment (decontamination andfiltering).

Advantages achievable with the present invention are anyway multiple andpermit to highly reduce the wear of the tool, consequently improving itsuseful life.

In particular, by using nozzles of the “airless” type, dimensions ofparticles are controllable so that they may result sufficiently smalland substantially homogeneous. Radius of each particle, in fact, isdirectly proportional to the surface tension of the fluid and isinversely proportional to constant or easily controllable factors, asfor example the fluid viscosity and the kinetic energy of particles, thelatter essentially depending on the supplying pressure and on the exitdiameter of the nozzle.

The possibility of controlling dimensions of particles, making themparticularly small and homogeneous, makes the heat exchange particularlyefficient because small particles quickly absorb heat from the tool andfrom the chip, and as much quickly they release it to surroundingenvironment. In fact, it has been found that temperature of thelubricating and cooling fluid, in the collection tank located under theworking area, does not increase, at the same time contributing inkeeping substantially unaltered chemical and physical properties of thelubricating and cooling fluid. In particular, it has also been foundthat atmosphere near the delivering area of atomized fluid undergoes arelevant temperature reduction compared to the environment, thuscontributing to make the heat exchange more efficient near the contactarea between the tool and the workpiece (or chip).

Moreover, by maintaining dimensions of particles particularly small, itis possible to realize a constant fluid flow particularly effective forreduction of friction at the chip-workpiece-tool interfaces.

Differently from known minimal systems, wherein particles are carried byan air flow, particles obtained by “airless” systems have their ownspeed. Absence of an air flow as a carrier, prevents rising up ofdrawbacks due to bouncing of the air flow described for the minimalsystems. This promotes deposition of the fluid in the area of interestand the consequent formation of a constant flow of lubricating andcooling fluid between the tool and the workpiece.

In this way, formation of fumes near the area of interest is highlyreduced, and even completely eliminated, with consequent improvementsrelated to safety of working environment and to ambient influence.

Another relevant advantage is given by the fact that, by improving thelubrication and cooling of the tool, it is possible to machine at highspeed, with consequent improvements in productivity.

BRIEF DESCRIPTION OF THE DRAWING

Further characteristics and advantages of the present invention will bemore evident from the following description, made simply as anexplanatory, non-limiting example, with reference to the sole FIG. 1,which schematically represents a lubricating and cooling deviceaccording to a possible embodiment of the present invention.

MODES FOR CARRYING OUT THE INVENTION

Device illustrated in FIG. 1 comprises a support element 10 for“airless” type nozzles 20 to deliver the lubricating and/or coolingfluid. Two “airless” type nozzles 20 are visible in FIG. 1, but it isopportune to consider that more than two nozzles may be provided, aswell as a single one, depending on workings to be done.

Jets from each nozzle 20 are directed toward the machining area, that istoward the rotating tool 2 (for example a milling tool), and generate ajet having a spray angle a typical of each nozzle.

Support element 10 is fixed in a known manner to a manufacturing machine1 and comprises a series of internal conduits 11 for supplying thelubricating and cooling fluid to nozzles 20.

The lubricating and cooling fluid is supplied under pressure through aduct 12 connected to a pump output (not shown) suitable for supplyingthe fluid at a pressure not higher than 150 bar and, preferably, betweenabout 5 and 70 bar.

“Airless” type nozzles, suitable for operating according to principlesof the present invention, are provided with a delivering orifice havinga diameter between 0.10 mm and 0.80 mm. Configuration of the jet ispreferably plan, with a fan shape, with a spray angle between about 10°and 80°, depending on the workings to be done and on dimensions of thetool.

The device of the present invention can be utilized with any type oflubricating and cooling fluid, used pure, mixed in water or in wateremulsion. Even if it is not expressly shown, a filter generally designedaccording to manufacturer's instructions is associated to the “airless”nozzles 20.

As an experimental example, a prototype of the device according to thepresent invention has been manufactured, mounting three equidistant“airless” nozzles on a support element 11 like that illustrated inFIG. 1. “Airless” nozzles have been adopted, produced by the companyWagner and sold with the commercial name “ProfiTip”, which have adelivering orifice of 0.48 mm, with a plan fan-shaped jet having a sprayangle equal to 40°. Utilized filters had a size of the mesh equal to 50μm.

As lubricating and cooling fluid it has been adopted a fluid produced byBLASER & CO. SA, delivered with the commercial name Blasocut BC20, mixedwith water at 5% in volume and supplied at a pressure of 10 bar.

The device has been applied to a machine provided with a milling tool.During the machining test, the flow rate measured for each nozzle was0.48 I/min.

During the test, total absence of fumes in correspondence of the workingarea has been observed, as well as the substantial absence of dropletsformed by cohesion on the workpiece and near the same. Also thetemperature of the lubricating and cooling fluid, in the collection tanklocated under the working area, has maintained substantially unaltered,this confirming the particular efficiency of the heat exchange of theatomized liquid according to the teachings of the present invention.

Useful life of the tool and the cutting speed are proved to be more thandoubled compared to the same parameters measured, with other conditionsbeing equal (tool, machined material, etc.), in case of adoption ofknown lubrication and cooling systems.

Another factor which gives evidence of the advantages of the presentinvention has been the observation of the shapes of the chips, whichresult less compressed compared to those generated during tests withknown lubrication and cooling systems. Because of the shape of the chipsdepending on the length and on the angle of the cutting plane, thismeans that the lubrication and cooling system according to the presentinvention results more effective also from the point of view ofreduction of the friction between the tool and the chip.

Although a lubrication and cooling system has been described as anexample wherein atomization is operated externally with respect to thetool, it is opportune to specify that principles of the presentinvention can be applied, with the same efficacy, also to lubricationand cooling systems provided within the tool, for example by providingat least an “airless” type nozzle put in fluid communication with aninternal channel located inside the same tool.

EXPERIMENTAL RESULTS

A device, substantially similar to that one just described, has beenoperated to perform tests in comparison with known lubrication andcooling systems. In fact several tests have been performed and repeatedat different working conditions, continuously changing the typology ofthe machining, of machined materials, of adopted inserts, etc.

In the following examples, which illustrate average values measured forsome of the most significant performed tests, performances of a systemaccording to the present invention have been compared to performancesprovided by currently known lubrication and cooling systems, inparticular by traditional systems using flexible and/or modular pipes todeliver the lubricating-cooling fluid in correspondence of the machiningarea.

In each test, the most important parameters of respective lubricationand cooling systems have been detected, i.e. the fluid flow rate, thesupplying pressure and the power absorbed by lubricating-coolingsystems. Concerning parameters related to the performances of thesystems, the following parameters have been detected:

Q (cm³/min): amount of chips removed in a minute, that is the parameterrepresentative of the productivity;

C_(p) (Process Capability): it is a numerical coefficient whichindicates the quality in time of the machining according to statisticalcriteria well known in the field;

Type of the tool wear: estimated according to the standard UNI ISO 8688;

Duration of the tool: generally expressed in minutes and eventuallycompared with production parameters, for example number of workpieces,covered distance expressed in meters, number of cuttings, etc.

Further details on standards and parameters regarding evaluations ofperformances herein disclosed can be found in “CUTTING TOOLS” by R.Edwards, published by The Institute of Materials—1993.

In all tests of lubrication and cooling systems, the same type of fluidhas been utilized. Also results of some tests are disclosed (Examples 4and 6) wherein comparison has been provided between performances of asystem according to the present invention and results of dry machinings.

EXAMPLE 1

Climb milling machinings of smoothing have been executed on hardened andtempered steel of the type UNI X20Cr13 having hardness equal to 330 HBand a specific cutting force equal to 2300 N/mm². In the systemaccording to the present invention, the lubricating-cooling fluid wasdelivered by way of three nozzles symmetrically disposed outside thetool.

Inserts adopted for the tool are produced by the firm WALTER andidentified by the code P2894-1 VTA 51.

Results of the executed machinings, expressed as average values on theset of the same tests, are listed in the following Table 1, wherein thefirst column quotes the parameters of the traditional lubrication andcooling system and the second one quotes the parameters of a lubricationand cooling system according to the invention. TABLE 1 System of theTraditional System invention Flow rate (l/min) 10 0.7 Pressure (bar) 230 System power (kW) 2.2 0.75 Q (cm³/min) 92 162 C_(p) 0.7 1.5 Type oftool wear CF* VB1-0.2** Useful life of the tool 30 min. 30 min.*CF: catastrophic failure (rapid deterioration of the operative partuntil its complete breaking - UNI ISO8688).**VB1-0.2: uniform flank wear with depth equal to 0.2 mm (deteriorationof normal type for the tool - UNI ISO8688).

As it can be seen, the flow rate of the lubricating and cooling fluid ishighly reduced to less than 1/10 compared to traditional systems.Moreover, considerable improvements have been achieved both from thepoint of view of the productivity (+75%) and from the point of view ofthe quality of the machining (+100%).

Also from examination of wear of the inserts, it is evident that asystem according to the present invention assures keeping of the toolintegrity. By the way, it is opportune to remind that a system accordingto the present invention permits to reduce replacements of tools and/orinserts, thus decreasing idle times necessary for the replacement andtherefore allowing further improving of the productivity of themachining process in its entirety.

The minor wear which inserts are subject to has permitted to machine anumber of workpieces (120 pieces) practically double with respect to thenumber of workpieces which has been possible to machine with knowninserts subject to traditional lubricating-cooling systems.

Moreover, relating to the piece machined under operation of thetraditional lubricating-cooling system, the need has been found forcarrying out a subsequent grinding working in order to removesuperficial waviness, while the workpiece machined under operation ofthe lubricating-cooling system according to the present inventionalready showed an optimal surface finish, that is a finish free fromwaviness and with roughness in accordance to required values.

EXAMPLE 2

Internal and external turning workings have been carried out on castiron of the type GG25 having hardness equal to 220 HB and specificcutting force equal to 1150 N/mm². In the system according to theinvention the lubricating-cooling fluid was delivered by a single nozzlenear the insert (internal adduction).

Inserts utilized for the tool are produced by the company SANDVIK withquality identified by the code GC3215.

Results of the performed workings, expressed as mean values of the setof the same tests, are quoted in the following Table 2, wherein thefirst column contains the parameters of the traditionallubricating-cooling system and the second one contains the parameters ofa lubricating-cooling system according to the invention. TABLE 2 Systemof the Traditional System invention Flow rate (l/min) 11 0.9 Pressure(bar) 8 60 System power (kW) 7.5 0.75 Q (cm³/min) 115 390 C_(p) 1.3 2Type of tool wear KT2-0.8* VB1-0.2** Useful life of the tool 30 min. 60min.*KT2-0.8: stepped crater wear of the cutting face with depth equal to0.8 mm.**VB1-0.2: uniform flank wear with depth equal to 0.2 mm.

Also in this case the flow rate of the lubricating-cooling fluid resultsto be always considerable lowered to less than 1/10 compared totraditional systems.

Moreover considerable advantages are achieved both for what concerns theproductivity (+240%) and for what concerns the quality of the machining(+50%).

From examination of the inserts wear, it is evident that a systemaccording to the present invention assures a constant quality of thetool: the useful life of the insert appears to be practically doubled.

EXAMPLE 3

Different drilling workings have been provided on the same material ofExample 2. In the system according to the invention thelubricating-cooling fluid was delivered by two nozzles directed towardthe cutting area.

Inserts utilized for the tool are produced by the company SANDVIK bothwith quality 53/3040 and with quality 53/1020.

Results of the provided workings, expressed as mean values of the set ofthe same tests, are quoted in the following Table 3, wherein the firstcolumn contains the parameters of the traditional lubricating-coolingsystem and the second one contains the parameters of alubricating-cooling system according to the invention. TABLE 3 System ofthe Traditional System invention Flow rate (l/min) 15 0.9 Pressure (bar)8 60 System power (kW) 7.5 0.75 Q (cm³/min) 128 305 C_(p) 1.3 2 Type oftool wear KT2-0.35* VB1-0.25** Useful life of the tool 60 min. 60 min.*KT2-0.35: stepped crater wear of the cutting face with depth equal to0.35 mm.**VB1-0.25: uniform flank wear with depth equal to 0.25 mm.

Also in this case the flow rate of the lubricating-cooling fluid resultsto be always considerable lowered to less than 1/10 compared totraditional systems.

Moreover considerable advantages are achieved both for what concerns theproductivity (+140%) and for what concerns the quality of the machining(+50%).

Also examination of the wear on inserts provides highly improved resultswith respect to the known technique: in fact it was possible to carryout 71 meters of drilling versus 30 meters obtained with inserts subjectto operation of a traditional lubricating-cooling system.

EXAMPLE 4

Bordering workings have been carried out on annealed steel of the typeAISI416 with hardness equal to 200 HB and specific cutting force equalto 1800 N/mm².

Comparison has been carried out between the dry machining and themachining subject to the action of the lubricating and cooling fluiddelivered by way of a system according to the present invention. Thistype of comparison has been provided because, for particular types ofmachining, materials and tools, dry machining is provided. Dry machiningis based on the assumption that the same chips, removed during themachining, contemporary permit to carry out heat and thus to remove theheat itself from the interface workpiece/tool.

The lubricating and cooling fluid of the system according to the presentinvention was delivered by a three nozzle system.

Inserts utilized for the tool are produced by the company SANDVIK withquality 2040.

The following Table 4 provides results of the tests as carried out.TABLE 4 System of the Dry machining invention Flow rate (l/min) — 2.4Pressure (bar) — 50 System power (kW) — 0.75 Q (cm³/min) 182 309 C_(p)0.2 1.5 Type of tool wear CF* VB1-0.15** Useful life of the tool 3 min.45 min.*CF: catastrophic failure.**VB1-0.15: uniform flank wear with depth equal to 0.2 mm.

Improvements in productivity (+70%) and, above all, in the quality ofthe machining (+650%) are immediately evident.

Aside from improving the tool quality, which tool is then less subjectto wear, another particularly interesting result comes from theconsiderable increment of the useful life of the insert (+1400%).

EXAMPLE 5

Different frontal grooving workings have been carried out on steel ofthe type AISI316 having hardness equal to 180 HB and specific cuttingforce equal to 2450 N/mm². In the system according to the presentinvention the lubricating and cooling fluid was in this case deliveredby a single nozzle.

Inserts adopted for the tool are produced by the company SANDVIK withquality GC235.

Results of the provided workings are quoted in the following Table 5.TABLE 5 System of the Traditional system invention Flow rate (l/min) 50.6 Pressure (bar) 5 50 System power (kW) (not detected) 0.75 Q(cm³/min) 51 59 C_(p) (not detected) (not detected) Type of tool wearCF* VB1-0.10** Useful life of the tool 19 min. 19 min.*CF: catastrophic failure.**VB1-0.10: uniform flank wear with depth equal to 0.10 mm.

The reduction of the flow rate of the lubricating-cooling fluid and theimprovement in the useful life of the inserts are confirmed.

EXAMPLE 6

Spherical turning workings have been provided on a brass alloy of thetype CuSn5Pb5Zn5-C with 100 HB hardness and specific cutting force equalto 700 N/mm².

As in the example 4, comparison was provided between the dry machiningand the machining subject to the action of the lubricating and coolingfluid delivered by way of a system according to the present invention.

The lubricating and cooling fluid of the system according to the presentinvention was delivered by a single nozzle system.

Inserts adopted for the tool are produced by the company SANDVIK withquality H13A.

The following Table 6 provides results of the tests as carried out.TABLE 6 System of the Dry machining invention Flow rate (l/min) — 0.4Pressure (bar) — 15 System power (kW) — 0.75 Q (cm³/min) 69 210 C_(p)1.3 2 Type of tool wear VB1-0.30* VB1-0.15** Useful life of the tool 114min 250 min*VB1-0.30: uniform flank wear with depth equal to 0.2 mm.**VB1-0.15: uniform flank wear with depth equal to 0.2 mm.

The productivity results considerably incremented (+200%), and also thequality of the machining results incremented (+50%).

1. A device for delivering a lubricating and/or cooling fluid near thecontact area between a tool and a workpiece being machined, comprisingat least a circuit for circulation of said fluid and delivering means todeliver said fluid near, or in correspondence of, the contact areabetween said tool and said workpiece, characterized in that saiddelivering means include one or more nozzles of the airless type toatomize said fluid.
 2. A device according to claim 1, wherein said oneor more nozzles have a delivering orifice having a diameter between 0.10mm and 0.80 mm.
 3. A device according to claim 1, wherein said one ormore nozzles have a fan shaped planar configuration of the jet.
 4. Adevice according to claim 3, wherein said one or more nozzles have aspray angle of the jet between 10° and 80°.
 5. A device according toclaim 1, wherein said circuit comprises means to supply said fluid tosaid one or more nozzles with pressures not higher than 150 bar.
 6. Adevice according to claim 1, wherein said circuit comprises means tosupply said fluid to said one or more nozzles with pressures betweenabout 5 bar and about 70 bar.
 7. A device according to claim 1, whereinsaid one ore more nozzles are externally arranged with respect to saidtool.
 8. A device according to claim 1, wherein at least one of said oneor more nozzles is in fluid communication with an internal duct providedin said tool.
 9. A method for delivering a lubricating and/or coolingfluid near the contact area between a tool and a workpiece beingmachined, wherein said fluid is supplied through a circuit and deliverednear, or in correspondence of, the contact area between said tool andsaid workpiece, characterized in that delivering of said fluid iscarried out by its atomization through one or more airless type nozzles.10. A method according to claim 9, wherein said one or more nozzles havea delivering orifice having diameter between 0.10 mm and 0.80 mm.
 11. Amethod according to claim 9, wherein said one or more nozzles have a fanshaped planar configuration of the jet.
 12. A method according to claim11, wherein said one or more nozzles have a spray angle of the jetbetween 10° and 80°.
 13. A method according to claim 9, wherein saidfluid is supplied to said one or more nozzles with pressures not higherthan 150 bar.
 14. A method according to claim 9, wherein said fluid issupplied to said one or more nozzles with pressures between about 5 barand about 70 bar.
 15. A method according to claim 9, wherein deliveringof said fluid by atomization is provided externally to said tool.
 16. Amethod according to claim 9, wherein delivering of said fluid byatomization is provided internally to said tool.